The present invention relates generally to fluid infusion systems, and more particularly to an improved system for detecting the formation of bubbles in such systems.
The infusion of fluids such as parenteral fluids into the human body is usually accomplished by means of a one-use disposable administration set which establishes a flow path between a reservoir of fluid to be infused and an injection site. Where the rate of administration is critical, such flow systems may include metering apparatus to establish a user-selected flow rate. Such metering is typically of either the cassette type, wherein an externally driven pump element is integrally included in the administration set, or of the peristaltic-type, wherein a section of tubing of the administration set is repetitively compressing and expanded. An example of the latter type of metering apparatus as described in U.S. Pat. No. 4,155,362, is marketed as the Model 2M8014 infusion pump by Baxter Travenol Laboratories, Inc., of Deerfield, Ill.
One problem which arises with the use of administration sets is that bubbles of air or gas contained in the sets may be inadvertantly infused along with the fluid, an occurrence which may be harmful or even fatal to the patient under certain circumstances. Bubbles may arise in the system as a result of improper set-up of the administration set or inadvertant depletion of the fluid source, or as a result of dissolved gases in the fluid being released as the fluid is subjected to pressure and/or temperature changes by the metering apparatus.
To prevent air or gas from being infused it has become common practice to provide a bubble detection system in the apparatus to automatically stop the apparatus should gas bubbles be detected downline of the metering apparatus. Such detection systems typically employ a light source and a light detector positioned on opposite sides of the administration set tubing to monitor the level of light transmitted through the tubing. Operation of the metering apparatus is interrupted and an alarm is sounded when the transmitted light level falls below a predetermined level.
One shortcoming of such bubble detection systems has been their inability to monitor both opaque fluids, such as blood components, and transparent fluids, such as medicinal solutions, without user-initiated conditioning to an appropriate operating mode. Not only did the necessity for such conditioning in prior art detection systems unduly complicate the set-up procedure, but it also introduced the possibility of inadequate protection should the systems be inadvertently conditioned for operation in the wrong mode.
The present invention is directed to a bubble detection system which is automatically conditioned to an appropriate operating mode for use with transparent and opaque fluids.
Accordingly, it is a general object of the present invention to provide a new and improved bubble detection system.
It is another object of the present invention to provide a new and improved bubble detection system operable in conjunction with both transparent and opaque fluids in a fluid infusion system.